We don't really know how to encourage healthy eating. Calorie counts on menus are a popular idea among health experts (and a requirement under the Affordable Care Act). But the evidence that they work is shaky at best. Research into other policy options, such as calorie taxes, subsidies for better food, and healthy food advertising, is limited. The work has tended to be second-hand or at 30,000 feet. It hasn't involved actual people in randomized trials.
That's what makes a new study involving 258 "lab rats" unusual. It compares various behavior-modifying techniques by giving people money to spend and seeing how they react.
After first asking all volunteers to view a food menu and make choices, researchers split the participants into groups and exposed them to one of six treatments: a menu on which unhealthy items were 20% more expensive; a menu on which healthy items were 20% less expensive; healthy food advertising; anti-obesity advertising; a combination of the tax and anti-obesity advertising; and a combination of the tax and healthy food ads. The lab rats had $10 to spend but could add in their $15 participation fee if they liked.
Three of the treatments proved effective in reducing calories, cholesterol, and carbohydrate intake. "The results indicate that the unhealthy foods tax, healthy foods advertising, and unhealthy foods tax combined with anti-obesity advertising significantly reduced the content of some nutrients of concern in meal selections," the paper says.
The tax plus anti-obesity ads combination had the most effect, statistically speaking. The other three—including anti-obesity ads on their own and the subsidy and healthy ad combo—were ineffective. And none of the treatments did much to reduce added sugar and salt consumption.
One of the researchers, Harry Kaiser, a professor of applied economics at Cornell, cautions that lab experiments don't necessarily translate to the real world. But he says they can be useful to show relative effectiveness.
Kaiser suggests we ditch the idea of healthy food subsidies (e.g. making salads cheap) and employ a grab-bag of other policies. "The way to fix the obesity problem will be a holistic mix of several policies, rather than just one policy," he says. "[That] includes positive food advertising, negative food advertising, limits to unhealthy advertising, menu labels, bans on junk food in schools, and excise taxes on products with added sugar, high fat, high sodium, and other unhealthy nutrients."
The team is now planning a larger volunteer-based study. Other countries, meanwhile, are going firmly down the tax route. France and Ireland have soda levies. Hungary has taxes on high salt, fat, and sugar products. And Mexico, where obesity rates are higher than in the U.S., recently approved a tax as well (Denmark, though, abandoned its measure last year when people crossed into Sweden to eat the same stuff anyway). Over time, these real-world experiments should give us a better idea of what works and what does not.